It is odd, disconcerting and occasionally amusing when children speak like grownups, parroting our jargon, our euphemisms, our lazy tropes.

Last year my youngest son was punched several times by a boy from another school on the 220 bus, but that's not how he described it. He said: "I was the victim of a sustained attack." He watches a lot of CSI.

The younger children are, the more alarming these incidents can be – it's proof they're paying attention the whole time, even if you thought adult discourse was as impenetrable to them as a foreign language.

When my eldest son was no more than four, he came into my office at home one afternoon and sat down in an old, broken armchair. "Is this the fucking chair?" he said. Through the long pause that followed I continued to stare at my computer screen while composing my features into a neutral expression. Finally I turned round and looked at him.

"Sorry, the what?" I said.

"The fucking chair that mum keeps telling you to get rid of," he said.